Apparatus for making organic fertilizer



April 22, 1952 E. w. EWESON APPARATUS FOR MAKING ORGANIC FERTILIZER 2SHEETS-SHEET 1 Original Filed Feb. 27, 1946 r e 0 m g llll IIIHII-HHII mw w L w k H n p 6 W a w z INVENTOR zdiaufi BY z/Qzzzmuz z W 7 ATTORNEYApril 22, 1952 E. w. EWESON 2,593,867

APPARATUS FOR MAKING ORGANIC FERTILIZER )riginal Filed Feb. 27, 1946 2SHEETS--SHEET 2 iNVENTOR ATTORNEY Patented Apr. 22, 1952 APPARATUS FORMAKING ORGANIC FERTILIZER Eric W. Eweson, Newport, R. I.

Original application February 27, 1946, Serial No. 650,610. Divided andthis application March 26, 1949, Serial No. 83,744

1 Claim.

This invention relates to apparatus for the making of organic fertilizerfrom organic waste materials.

This application is a division of my copending application Serial No.650,610, filed February 27, 1946, now Patent No. 2,474,833.

It is an object of the invention to provide apparatus for increasing therapidity of propagation of aerobic bacteria in a mass of moist organicmaterial, whereby the decomposition of the organic material and thepreparation of a completed fertilizer product may be hastened.

It is a further object of the invention to provide for drying of thoseportions of the moist, decomposing mass in which decomposition hasproceeded to the desired extent, in order to prepare a finished productof such dryness that further developement of bacteria is arrested untilthe fertilizer product is added to the soil or is again moistened.

Other objects and advantages of the inven tion will appear hereinafter.

A preferred embodiment of apparatus is shown in the accompanyingdrawings, in which,

Figure l is a vertical section through the apparatus.

Figure 2 is a section on the line 22 of Fi ure 1.

Figure 3 is an enlarged section through one of the air distributorpipes.

Figure 4 is a similar view showing a modified form of air distributorpipe.

In practicing my invention I use one or more of the organic materialsnow commonly used for the purpose, such materials usually being waste orrefuse materials which are of little or no value for other purposes.Suitable materials include garbage, sludge, manure, waste and refusefrom canning, fishery and sugar mills, refuse and waste fromdistilleries and breweries, weeds, straw, tobacco stems, wood wastes,peat and the like.

Such materials usually contain sufiicient moisture for efficientfermentation, i. e. a moisture content preferably in the neighborhood of50% to 60%, although satisfactory results may be obtained with amoisture content as low as 40% or as high as 80%. Comparatively drymaterials are advantageously mixed with very wet materials to obtain apreferred moisture content at the mass.

Suchorganic materials are first subjected to a cutting or grindingoperation to reduce the size of the pieces of solid material to uniform,relatively fine condition, and the cut or ground mass is then inoculatedand thoroughly mixed with a seed stock of aerobic soil bacteria inaccordance with known practice. If desired, certain nutricuts andminerals such as nitrates, urea, ammonium salts, phosphates, lime andthe like may also be added at this time, in accordance with knownpractice.

In the past, it has been the practice for cen turies to convert organicmaterials into soil fertilizers by composting, the organic materialsbeing inoculated with stable manure, fertile garden soil or othercompost material. In composting it has been recognized that aeration ofthe decomposing mass was important, and aeration has usually beeneffected merely by occasionally turning over a portion of the heap,although in some cases grilled receptacles have been provided whichassist aeration of the mass. The desirability of temperature control hasalsobeen recognized, and in some cases crude methods such as coveringthe heap with straw or burlap have been used to advantage.

In composting, however, decomposition proceeds relatively slowly evenunder the best of conditions. More recently improved methods andapparatus have been proposed and used in which the conditions are bettersuited to induce rapid decomposition, and in which the condi tions maybe controlled to some extent. In the apparatus referred to, moistorganic material, properly inoculated, is fed to a digester containing aseries of spaced, superposed decks, each of which is adapted to containa layer of material about a foot thick. Air is introduced into, thedigester between the decks so that the surface of each layer of organicmaterial is exposed thereto. Mechanical means such as plows are providedfor stirring the material on the decks and for causing the material tomove successively downward from one deck to the next lower deck;Digesters of this type are, however, relatively expensive, and themechanical complications are considerable. The rate of propagation ofbacteria is also relatively slow, due to the fact that aeration isuneven, the exposed surface portions of the material being excessivelyaerated while the unexposed portions suffer :fro'minadequate air supply,both of which conditions hamper optimum developement of aerobicbacteria. Since the fertilizing value of the end product dependsprimarily on the synthesis and accumulation of micro organic protoplasm,in which are contained the nutrients needed by the plants, fermentationmust be as efficient as possible. This cannot be satisfactorily andquickly accomplished by presently known methods.

According to the present invention I place a mass of moist, inoculatedorganic material in a tank or container adapted to enclose and supportthe same, and I force air under pressure through said mass fromunderneath in order to furnish an adequate and controlled supply of airto all portions of the mass, the flow of air and the temperature of theair being controlled to provide conditions best suited for efficientpropagation of baceteria and for subsequent drying of the mass.

Furthermore I withdraw spent air, i. e. air in which oxygen and in somecases the nitrogen content has been substantially reduced, and gaseswhich may be generated during the fermentation process, notably excesscarbon dioxide, from a plurality of points spaced at intervalsthroughout the mass.

Furthermore, I may, when desirable, agitate the mass slightly asdecomposition proceeds to break upair channels to facilitate the uniformdistribution of fresh air to all portions of the mass, and to facilitatethe withdrawal of spent air and generated gases as previously referredto.

The fresh air which is'forced' through the mass is preferably preheatedto a temperature best suited for optimum propagation of the variousstrains of aerobic bacteria contained in the mass. Such temperature maybe between 90 F. and 150 F. depending on'the stage of fermentation, theparticular type of microbic development to be stimulated, the degree ofdrying desired, and on other conditions as observed by the operator.

No satisfactory fixed rule may be laid down as to the quantity of airintroduced, for this will also vary depending on the nature'of thematerials and the stage of fermentation, but it may be noted that thequantity of air required is much less than that customarily used in theprior process above referred to. In general, it may be said that cubicfoot of air per minute per cubic foot of material is the maximumpermissible volume of air, and the volume used to facilitate optimumaerobic fermentation will vary within this maximum depending onconditions. A skilled operator, observing' the process of thefermentation, will be able to adjust the temperature, quantity anddistribution of air as required for efficient operation, it beingimportant to note that any excessive blowing of air through thefermenting mass hampers optimum development of aerobic bacteria bydisturbing the osmosis and by preventing the slight accumulalion ofcarbon dioxide desired as an aid in dissolving nutrient minerals neededby the bacteria. The carbon dioxide content in the spent air withdrawnis, in fact, a good indication of proper aeration and fermentation, forwhen the carbon dioxide content is only around 1% it is a sign of poorfermentation, which may well be due to excessive aeration.

After fermentation and decomposition has proceeded to the desired point,which will first occur in the lower part of the tank, rapid drying ofthis-material is desired and is greatly facilitated by continuing toforce air under pressure through this mass of material. This more orless humid air will not be spent air and will benefit the next layers ofthe material in the same way as fresh air.

Referring to the drawings, I provide a large tank l, preferablycylindrical in shape, having an open top into which the organic materialmaybe fed as desired, and having a closed conical bottom I 2 providedwith a valve 3 through which the finished fertilizer may be discharged.

An air distributor 4 is located in the lower part of the tank, extendinghorizontally across the tank. This distributor may be of any suitabledesign, but as shown consists of a header having a series of distributorpipes 6 projecting therefrom, each of said distributor pipes having aseries, of small air vents l drilled therein, preferably on the underside, as shown in Figure 3, so that said holes are less likely to becomeclogged by the mass of material above. Alternatively, larger holes maybe drilled in the upper side of the pipes 8 in each of which may bemounted a fitting, as shown in Figure 4, comprising a tube 3 having airvents 9 covered and protected by the head ID. The distributor pipes maybe supported by suitable cross bars I l.

The air distributor is connected to a compressor unit 12, which in turn,may be connected to a heating unit I 3 in which the incoming air may beheated as described'to maintain the desired temperature. The rate offlow of air to the distributor may be controlled by valve I l.

, The withdrawal of spent air and generated gases is accomplishedthrough a series of air collectors i, designed like air distributor 4,and having collection pipes 5 similar to pipes 6, said air collectorsextending horizontally across the tank at suitably spaced intervals, thewithdrawal being controlled by valves 15.

Although there will be a continuous downward shifting of the mass ofmaterial in the tank as a result of the dehydration and decomposition ofthe material, and as a result of the periodic Withdrawal of finishedmaterial, it may be desirable, especially in tanks of considerableheight, to provide-for additional agitation or stirring of the material.This may be accomplished by supporting a vertical shaft iii in upper andlower cross bars I! and 18, said shaft carrying a plurality of arms l9,spaced at suitable intervals along the shaft. This agitator is mountedfor relatively slow rotation in the tank in any suitable manner, as bybevel gears 26 and 2| from the shaft 22 which may be driven by the motor23 through pulleys 24 and 25 and belt 26. -If desired the shaft may beprovided with an extension 21 carrying a bar 28 to stir the readymaterial below air distributor 4 to facilitate discharge of thismaterial through valve 3.

The tank may also be provided with a plurality of sampling ports 29consisting of short pieces of pipe extending inwardly, through whichthematerial may be sampled and the temperature observed from time totime. Such ports are normally closed during the operation and are onlyopened from time to time as required.

In the operation of the apparatus, a mass of inoculated organic materialis placed in the tank and air under suitable pressure is forced throughthemass by the compressor unit, the air being well distributed by thedistributor 4, and the temperature of the incoming air beingcontrolledas required. As fermentation proceeds withdrawal ofspent airand generated gases is controlled by valves l5. For example, if all ofthe valves I5 are closed, all of the incoming air is forced upwardthrough the entire mass and the spent air and generated gases willescape at thetop of the tank. On the other hand, if one or moreof thevalves [5 are opened, part of the air and generated gases will bewithdrawn through the exit passages thus provided. As decompositionproceeds, a skilled operator, observing the conditions at various levelswithin the tank, will adjust the valves IS in such manner that thedistribution and withdrawal is properly adjusted to the requirements ofthe mass at various levels.

The operation may be carried out as a batch operation but is preferablypracticed as a continuous operation. In the latter, of course, thefertilizer is removed either continuously or periodically from thebottom and new material is added continuously or periodically at thetop.

At the very beginning of a continuous operation, the material in thebottom of the tank below the air distributor would receive substantiallyno treatment, of course, and as discharged from the tank would either bediscarded or returned to the top of the tank for treatment. As thoperation begins, decomposition should be most active in the layerimmediately above the air distributor, and at this stage the valve l5 ofthe lowest air collector would be opened comparatively widely. Asdecomposition proceeds, however, the continued introduction of fresh airbegins to dry the lowest material, and as drying proceeds, decompositionwill be progressively inhibited. As this occurs the valve of the lowestair collector may be closed, thus forcing the air to pass into the Ilayer next above, and the valve [5 controllin withdrawal of air fromthis layer would be opened. Alternately, instead of closing the valve l5controlling the withdrawal of air from the lowest layer, this valve maybe left open, and the volume of air introduced through the valve I4 maybe increased to force the air into the layer above. This has theadvantage of hastening drying of the material in the lowest layer. In nocase, however, should the volume of air forced into the upper layerswhere decomposition is taking place exceed the permissible maximum aboveset forth. As final drying of the lower layer proceeds, however,decomposition becomes so limited that the air reaching the layer aboveis substantially fresh air, although it is somewhat humidified by itspassage through the lower layer. Gradually, in this way, by controllingthe valves l5, fresh air is forced higher and higher until substantiallyall of the contents of the tank are under treatment, the lower layersbeing dried and the upper layers being in a state of progressivedecomposition from the top toward the bottom. After a state ofequilibrium is established, finished dried fertilizer may be withdrawnfrom the bottom of the tank and additional new material may be added tothe top of the tank from time to time. Throughout the operation, aspreviously explained, the valves [5 may be adjusted from time to time tosuit the requirements of the mass at various levels.

It will be understood that the invention may be variously modified andembodied within the scope of the subjoined claim.

I claim as my invention:

Apparatus for making organic fertilizer by the decomposition of moistorganic material through the propagation of aerobic bacteria comprising,a tank, means for forcing air under pressure into said tank at thebottom level only of the mass of organic material in said tank, aplurality of outlet conduits located at a plurality of levels withinsaid tank for withdrawing spent air and generated gases at verticallyspaced intervals throughout said mass, and agitator means comprising aplurality of arms mounted for movement within said tank, one of saidarms being located above the level of each of said conduits.

ERIC W. EWESON.

REFERENCES CITED The following references are of record in the file ofthis patent:

' UNITED STATES PATENTS Number Name Date 309,485 Munzinger Dec. 16, 18841,910,793 Guinan May 23, 1933 2,027,268 Davis Jan. 7, 1936 2,209,613Roeder July 30, 1940 2,299,299 Bills Oct. 20, 1942

